2020 Volume 40 Issue 3 Pages 239-249
Misidentification of persons in dementia is a symptom of delusionally misidentifying familiar persons who are “obviously understandable”, in the stage where generalized cognitive impairment is not so severe. By speculating the patientsʼ subjective experiences from their behavior and “narrative”, the following inferences are made about the pathogenesis underlying this peculiar symptom. Misidentifications occur more frequently in DLB than in AD, which suggests that some biological factors work. The misidentification observed in DLB is characterized by a co-occurrence of duplication phenomenon, which in turn may be caused by the fluctuation of the arousal level that makes it difficult to distinguish between imagination and reality.
In AD the psychological factor is presumed to mainly work as a cause of misidentification symptom. That is subconscious craving to escape from the unpleasant present situation, and to make a harsh reality temporarily less distressing. In also DLB, the psychological factors work as in AD, and in AD, vise versa, the biological factors work as in DLB. Ultimately speaking, the misidentification of persons observed in dementia is thought to have an adaptive role for patients in severe mental distress.
